Eaton SmartWire-DT, Manual

Page: 44 / 130

Engineering
40
02/11 MN05006002Z-EN
X
Calculate the supply voltage at the SmartWire-DT slave
“Slave n” using the formula:
X
If the calculation with the above formula has yielded too
low a supply voltage at “TIn. n”, calculate the supply
voltage at the individual SmartWire-DT slaves using the
table „Step-by-step calculation of the supply voltage“,
page 40.
Table 10: Step-by-step calculation of the supply voltage
U
n
= U
n-1
- R
Ln
x (I
n
+ I
RB
)
h
If this rough calculation yields an excessively low supply
voltage at an SmartWire-DT slave “n” does it have to be
calculated as of what network position the minimum
supply voltage U
VPmin
= 10.5 V DC is achieved. An addi-
tional power feeder module EU5C-SWD-PF2-1 has to be
inserted into the SmartWire-DT network before this posi-
tion.
Smart-
Wire-DT
slave
(slave
address) Step 1:
Determining the
current in the
line segment Step 2:
Determining the
resistance of the
line segment as
of the previous
slave Step 3:
Determining the
voltage drop in
the line segment Step 4:
Determining
the supply
voltage of
the current
slave
SWD (1) I
G
=I
1
+ I
2
+ …
I
n
+ I
RB
R
L1
= R
L
x L
1
U
L1
= I
G
x R
L1
U
1
= U
V
- U
L1
SWD (2) I
2
= I
G
- I
1
R
L2
= R
L
x (L
2
- L
1
) U
L2
= I
2
x R
L2
U
2
= U
1
- U
L2
SWD (3) I
3
=I
G
- I
2
R
L3
= R
L
x (L
3
- L
2
) U
L3
= I
3
x R
L3
U
3
= U
2
- U
L3
… … … … …
SWD (n) I
n
= I
G
- (I
1
+ I
2
+
… I
n
+ I
RB
)
R
Ln
=
R
L
x (L
n
- L
n-1
)
U
Ln
= I
n
x R
Ln
U
n
=
U
n-1
- U
Ln
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